A number of agents have begun testing for this project. One agent, a MEK inhibitor, has been evaluated as a radiation sensitizer both in vitro and in vivo. The agent was found to sensitize three histologies to radiation in vitro and to sensitize two tested cell lines to radiation in subcutaneous xenografts. Additional mechanistic work has revealed that the cause of this senstization appears to be related to abrogation of the G2 checkpoint after irradiation. Additional work with this compound is focusing on possible biomarkers of effect to identify candidate markers of efficacy for clinical translation. In addition, we are currently testing the agent in compbination with other targeted agents or with chemotherapy. Two additional agents are currently undergoing testing for efficacy as radiation sensitizers. These include a small molecule poly(ADP-ribose) polymerase (PARP) inhibitor and a multi-target tyrosine kinase inhibitor. The preliminary in vitro clonogenic assays have been promising for these two compounds. Additional in vitro work, in vivo work, and mechanistic work will be ongoing. The eventual goal for these compounds is clinical translation into trials as radiation sensitizers.